Montelukast Arrow (Montelukast)

Montelukast is a leukotriene receptor antagonist used to treat conditions mediated by leukotriene‑driven inflammation.

• Asthma: Improves long‑term control and reduces the frequency of asthma attacks.
• Allergic rhinitis: Relieves nasal congestion, sneezing and itchy eyes associated with seasonal allergies.
• Exercise‑induced bronchoconstriction: Prevents airway narrowing triggered by physical activity.

• Montelukast selectively blocks the cysteinyl leukotriene receptor CysLT1, preventing leukotriene D4 from binding. By inhibiting this receptor, it reduces leukotriene‑mediated bronchoconstriction, vascular permeability, mucus secretion and inflammatory cell recruitment in the airways, thereby improving respiratory function and decreasing allergic inflammation. The antagonism is dose‑dependent and persists for the duration of the dosing interval, providing consistent protection against leukotriene‑driven airway changes.

Montelukast may cause a range of adverse reactions, most of which are mild and reversible.

Common Side Effects

• Headache: mild to moderate headache that may resolve without treatment.
• Upper respiratory tract infection: symptoms such as sore throat, runny nose or mild fever.
• Abdominal pain: stomach discomfort or cramping that is usually transient.
• Diarrhea: loose, watery stools occurring intermittently.
• Cough: non‑productive cough episodes without significant phlegm.

Serious or Rare Side Effects

• Allergic reactions: rash, urticaria, or angioedema that may require medical attention.
• Neuropsychiatric events: agitation, anxiety, depression, or suicidal thoughts reported in rare cases.
• Hepatotoxicity: elevated liver enzymes or hepatitis signs needing monitoring.
• Stevens‑Johnson syndrome: severe skin blistering and mucosal involvement, a medical emergency.
• Churg‑Strauss syndrome: rare eosinophilic vasculitis presenting with asthma worsening and systemic symptoms.

When prescribing Montelukast, clinicians should consider several precautionary measures to ensure safe use.

• Assess asthma control: confirm that the patient requires maintenance therapy beyond inhaled corticosteroids.
• Monitor for neuropsychiatric symptoms: watch for mood changes, depression or suicidal thoughts.
• Evaluate liver function: consider baseline tests in patients with hepatic impairment.
• Use in pregnancy: prescribe only if the potential benefit justifies the potential risk, as safety data are limited.
• Use in lactation: weigh benefits against unknown effects on nursing infants.
• Store at ambient temperature: keep below 25 °C in the original packaging, protected from moisture.

Montelukast can interact with other medicines, altering its effectiveness or increasing adverse effects.

Major Interactions (Avoid)

• Phenobarbital: may reduce montelukast plasma concentrations.
• Rifampin: strong enzyme inducer that can lower drug exposure.

Moderate Interactions (Monitor Closely)

• Antidepressants (SSRIs, SNRIs): may increase risk of neuropsychiatric events.
• Antifungal azoles (ketoconazole, itraconazole): can raise montelukast levels.
• Warfarin: occasional reports of altered INR, monitor coagulation.
• Oral contraceptives: may slightly increase montelukast exposure, observe for side effects.